Epilepsy is a neurologic disorder that causes those afflicted to have seizures. Sometimes external stimuli trigger the seizures. For example, those with photosensitive epilepsy (PSE) have an increased likelihood of experiencing a seizure when exposed to pulsating light or patterns that include strong contrast of light and dark areas. Even if not seizure inducing, pulsating, flashing, or high contrast images may cause visual discomfort to viewers of video, such as broadcast on television or shown in movie theaters. The flashing images may be due to video content and/or effects of video processing. Some countries require that broadcast video be pre-screened for such PSE triggers. The current requirements dictate that video be checked for flashing and checkerboard or bar type patterns with more than 20 nit differences over more than one quarter of the screen. Although an International Telecommunication Union (ITU) standard includes for checking of flashing, there is no detection method outlined other than suggesting a manual approach: viewers watch video using ITU-R BT.500 specified home viewing conditions and determine if the video seems to have flashes, etc. Nor are the guidelines inclusive of all PSE triggers.
One marketed product, Cambridge Research Systems' Harding Flash and Pattern Analyzer claims to screen for triggers following the guidelines, which means it likely searches video for temporal (flash) or spatial (bar or checkerboard) pattern detection.
No current systems, however, analyze video images and produce quantitative indications, predictions, alarms, and causes of visual discomfort. Further, there is no device that actively detects video having scenes that could possibly trigger PSE seizures, and actively mitigates such scenes.
Embodiments of the invention address this and other limitations of the prior art.